This invention provides a particularly advantageous process for preparing triphendioxazine compounds and particularly advantageous intermediates.
European patent application EP 0889046 A1 describes symmetrically disubstituted triphendioxazine compounds of the following general formula (I) 
where the rings marked A are inter alia linearly fused in positions 2, 3 and 9, 10 with rings having complementary members including of the formulae xe2x80x94NR1xe2x80x94(CO)mxe2x80x94NHxe2x80x94 and xe2x80x94NR1xe2x80x94(CO)mxe2x80x94Oxe2x80x94; where R1 is hydrogen, C1-4alkyl or phenyl, preferably hydrogen, methyl or ethyl; and m is 1 or 2.
The preparative process disclosed in EP 0889046 A1 proceeds from intermediates, i.e. amino compounds, which are ortho-substituted by an alkoxy group and obtainable only by a relatively complex synthesis. The process described is characterized by the use of 2,3,5,6-tetrachloro-1,4-benzoquinone and leads to intermediates which are chlorinated on the central ring. The ring closure reaction proceeds by dechlorination and leads to the chlorine-free triphendioxazine compounds of the general formula (I). The condensation reaction does not generally lead completely to the chlorine-free compounds of the formula (I); it virtually always by-produces a certain amount of monochloro and dichloro compounds.
It is an object of the present invention to provide a process which proceeds from readily available intermediates that are not chlorinated on the central ring and leads via nonchlorinated intermediates to the desired triphendioxazine compounds which are completely chlorine-free on the central ring.
It was surprisingly determined that even amino compounds which are not substituted in the ortho position are useful as intermediates, provided the cyclization taking place following the reaction with a benzoquinone is carried out according to the invention using manganese dioxide and 80 to 100% strength, preferably 90 to 95% strength, sulfuric acid. It is also unexpected that the cyclization is not accompanied by a sulfonation on the central ring, but provides the triphendioxazine compounds of the general formula (I) directly.
The reaction of 1 mol of a compound of the general formula (II) 
where R3 is hydrogen, C1-10alkoxy, halogen or hydroxyl, with 2 mol of a compound of the general formula (III) (=intermediates) 
where the ring marked A is linearly fused in position 3, 4 with a ring having a complementary member of the formula xe2x80x94NR1(CO)mxe2x80x94NR2 or xe2x80x94Oxe2x80x94COxe2x80x94NR2; m is 1 or 2; and R1 and/or R2 are each independently hydrogen, a C1-8alkyl radical, a substituted or unsubstituted phenyl, benzyl, naphthyl or benzanilide radical, a substituted or unsubstituted C5-6cycloalkyl radical or a radical of the formula 
is followed as a characterizing step by a cyclization carried out using manganese dioxide(MnO2) and 80 to 100% strength, preferably 90 to 95% strength, sulfuric acid.
Preferred compounds of the general formula (III) are 
where R1 and R2 are each as defined above.
The condensation reaction of compound (II) with compound (III) or (IIIa-d) is carried out in a solvent in the presence of an inorganic or organic acid as a catalyst between 50 and 160xc2x0 C. It may also be carried out in water or glacial acetic acid. The condensation reaction leads to intermediates of the general formula (IV), where the rings marked A are defined as above for formula (III). 
The advantage of this process is that it is possible to proceed from the intermediates (III) or (IIIa), (IIIb), (IIIc) and (IIId) which, unlike the amino compounds bearing an alkoxy group in the ortho position, are relatively simple to obtain. Starting compound (II) is preferably 2,5-dihydroxy-1,4-benzoquinone.
Preferred solvents for the condensation reaction are high-boiling solvents such as, for example, N-methylpyrrolidone, dimethylformamide or orthodichlorobenzene.
The preparation of the intermediates (IIIa), (IIIb), (IIIc) and (IIId) is described in EP 0911337 A1.
Preferably R1 and R2 are each independently hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclohexyl, a substituted or unsubstituted benzanilide radical, naphthyl, a radical of the formula 
an unsubstituted phenyl radical or a phenyl radical which is substituted by one or more substituents selected from the group consisting of halogen, preferably chlorine, nitro, phenyl, C1-8-alkyl, preferably C1-4-alkyl, and C1-2-alkoxy.
The abovementioned substituted phenyl radical in the definition of R1 and R2 is preferably a radical of the formulae (a) to (q) 
The abovementioned substituted benzanilide radical in the definition of R1 and R2 is preferably a radical of the formulae (r) and (s) 
Particularly preferred compounds of the formula (III) are compounds conforming to the following formulae (1) to (18): 
Triphendioxazine compounds of the formula (I) which are prepared by the process according to the invention are used as pigments.
The pigments prepared according to the process of the invention are very useful for coloring plastic materials, by which are meant solvent-free and solvent-containing materials comprising plastics or synthetic resins (in oil-based or water-based paints, in coating materials of various kinds, for spin dyeing viscose or cellulose acetate or for pigmenting plastics, for example polyamide, polyethylene, polystyrene, polyvinyl chloride, rubber and artificial leather). They may also be used in printing inks for the graphical industry, for the coloring of paper materials, for the coating of textiles or for pigment printing.
They may also be used in cosmetics.
The colorations obtained are notable for their excellent heat, light and weather fastness, chemical resistance, color strength and very good application properties, for example crystallization resistance and dispersing fastness, and especially for their fastness to migration, bleeding, overcoating and solvents.
In addition, the pigments prepared according to the process of the invention are also useful as colorants in electrophotographic toners and developers, for example one- or two-component powder toners (also known as one- or two-component developers), magnetic toners, liquid toners, polymerization toners and further specialty toners (ref.: L. B. Schein, xe2x80x9cElectrophotography and Development Physicsxe2x80x9d; Springer Series in Electrophysics 14, Springer Verlag, 2nd edition, 1992).
Typical toner binders include addition polymerization, polyaddition and polycondensation resins, such as styrene, styrene acrylate, styrene butadiene, acrylate, polyester, phenolic and epoxy resins, polysulfones, polyurethanes, individually or in combination, and also polyethylene and polypropylene, in or to which further ingredients, such as charge control agents, waxes or flow auxiliaries, may be present or added subsequently.
A further application area for pigments prepared according to the process of the invention is their use as colorants in powders and powder coating materials, especially triboelectrically or electrokinetically sprayed powder coating materials, which are used to coat the surfaces of articles made, for example, of metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber (J. F. Hughes, xe2x80x9cElectrostatics Powder Coatingxe2x80x9d, Research Studies Press, John Wiley and Sons, 1984).
Powder coating resins employed are typically epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane resins and acrylic resins together with customary curing agents. Combinations of resins are also used. For instance, epoxy resins are frequently used in combination with carboxyl- and hydroxyl-containing polyester resins. Typical curing agent components (depending on the resins system) are, for example, acid anhydrides, imidazoles and dicyandiamide and derivatives thereof, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.
The pigments prepared according to the process of the invention are also useful as colorants in inkjet inks, both aqueous and nonaqueous, and in those inks which operate according to the hot-melt process.